FIGS. 11(a) to (c) show a structure for connecting an electric wire to a terminal described in connection with Patent Document 1.
First, as shown in FIG. 11(a) and FIG. 11(b), in relation to a structure for connecting an electric wire to a terminal, a metallic, saclike cap 230 of a size to cover an area ranging from a conductor Wa (made up primarily of a stranded wire created by twisting a plurality of wires) stripped by peeling off an insulating sheath Wb to a portion of an electric wire covered with the insulating sheath Wb is attached to an end of an electric wire W. The conductor Wa at the end of the electric wire W covered with the cap 230 is put on a bottom plate 221 of a wire connecting region 212 formed in a rear of the terminal 210. In this state, as shown in FIG. 11(c), a pair of conductor crimping pieces 222 extending upward from both side edges of the bottom plate 221 are folded inward so as to warp the conductor Wa and the cap 230 and then crimped and fixed such that the conductor Wa and the cap 230 are brought into close contact with an upper surface of the bottom plate 221.
In the cap 230, a portion 231 that fits around an outer periphery of the conductor Wa is formed into a small-diameter cylindrical shape, and an entrance-side portion 232 that fits around an outer periphery of the insulating sheath Wb is formed into a large-diameter cylindrical shape. A clearance gap existing between the conductor Wa and the cap 230 is filled with a (un-illustrated) waterproof filler. Serrations 228 for enhancing contact conduction between the cap 230 and the terminal 210 are provided on an internal periphery of the wire connecting region 212 of the terminal 210.
The cap 230 is used here for the following reasons. For instance, provided that the conductor Wa of the electric wire W is made of aluminum or an aluminum alloy and that the terminal 210 is made of copper or a copper alloy, if a water content adheres to a contact are (i.e., a crimping region) between dissimilar metals, electrical corrosion may occur. In order to prevent this, a material of the cap 230 is set to a substance of the same type (copper or the copper alloy) as that of the terminal 210. Although either a terminal made of aluminum or a terminal made of an aluminum alloy can also be used for an aluminum wire, both the terminal 210 and the cap 230 are made of copper or a copper alloy for reasons that a terminal made of copper or a terminal made of a copper alloy has an advantage in strength. When the material is selected as mentioned above, the cap 230 and the conductor Wa of the electric wire W become dissimilar metals (the cap is made of copper or a copper alloy, and the conductor is made of aluminum or an aluminum alloy). However, the clearance gap between the conductor Wa and the cap 230 is filled with the filler as mentioned above, to thereby prevent intrusion of the water content into the cap 230. Accordingly, a fear of electrical corrosion has hitherto been said to be eliminated.
A tubular cap is normally used as the cap 230. A cap subjected to drawing or cutting so as to close its leading end is usually used.